The present invention relates to a new and improved winding apparatus for forming laps and which is of the type containing at least one rotating winding roll or roller and a given or predetermined number of calender rolls for compressing a fiber sheet into a windable web (or "sheet").
Laps serve as feed material for ribbon lap machines and for the subsequent combing process.
Calender rolls serve for compressing a fiber web in order to enable unwinding of the lap without mutual felting of the web portions. In order to obtain good fiber web compression, the web should undergo at least two compression stages or operations before there is carried out the formation of the lap.
In order to take up the extension or elongated portion of the web, which arises due to the compression, and in order to obtain a small degree of drafting of the web from one compression passage to another, the circumferential speed of the calender rolls can be slightly increased from calender roll to calender roll.
The aforementioned drafting of the web advantageously takes place with the web lying on the associated calender roll in order to thereby provide the fibers with guidance, that is a so-called stroking effect, and also in order to avoid so-called springing-back (also called breathing), that is to say a partial cancellation of a preceding compression.
Such arrangements of calender rolls have been disclosed in German Patent No. 644,119, granted Apr. 8, 1937, and British Patent No. 711,599, granted July 7, 1954.
In these patents, the calender rolls are disposed one above the other in a vertical arrangement. It is known that the calender rolls disclosed therein, the shaft bearings of which are guided in slide rails, are supported upon each other with their whole weight.
This arrangement has the disadvantage that during possible idle running of the calender rolls or rollers, that is without a web lying between them, on the one hand the rollers rub against each other as a function of their different peripheral speeds, and, on the other hand, upon formation of a lap about a calender roll, that is upon occurrence of a defect, the calender rolls must be lifted away from one another in order to free the relevant calender roll of the lap.
In order to eliminate these two disadvantages, or at least to eliminate them to a large extent, an arrangement of calender rolls has been proposed in which two calender roll pairs are arranged next to one another and the aforesaid vertical arrangement is only used per calender roll pair.
Such arrangements are disclosed in U.S. Pat. No. 2,502,894, granted Apr. 4, 1950, and in German Patent No. 629,355, granted Apr. 9, 1936.
The advantages achieved by the last-mentioned calender roll arrangement are, however, at least partially obtained by accepting the aforementioned disadvantage that the web no longer is guided in the drafting zone between the two roller pairs, and this, in turn, leads to the aforedescribed "breathing" phenomenon.